Electrical heating unit



Feb. 10, 1925.

L. E. STEINER ET AL ELECTRICAL HEATING UNIT Filed 001;. 20, 1923 Patented Feb. 10,1925.

UNITED STATES PATENT OFFICE.

LEONARD E. STEINE R AND FLOYD 1. SMITH, OF BRONX, NEW-YORK.

ELECTRICAL HEATING UNIT.

Application filed October 20, 1923. Serial No. 669.718.

'To all wlmm it may concern:

Be it known that we, LEONARD E. STEINER and Fmro P. SMITH, citizens of the United States. both residing at the Bronx. county of Bronx, and State of New York, have invented a certain new and useful Electrical Heating Unit, of which the following is a specification.

This invention is an electrical heating unit adapted to be used in various environments wherein it is desired to convert electrical current into heat through the employment of a resistance coil, and is particularly adapted for use where space is limited and where the maximum amount of heat is desired for minimum displacement by the apparatus or unit utilized for producing such heat.

The object of the invention is to provide a'unit which may he made very small and compact although, manifestly, it can be made in larger sizes if desired for heavier duty.

' A further object of the invention is to produce a unit of the character described wherein current carrying leads extending exteriorly of the unit are eliminated.

In electrical heating units as new constructed and particularly in connection with the smaller units, it is the universal practice to feed the current to the unit through wire leads extending therefrom, these wire leads being connected to the current source or feed wires by twisting the respective wires together. In practice it is found that after an astonishingly short period these leads break off and render the unit unfit for further use and require it to be discarded or taken apart and repaired.

In accordance with this invention, there are no extraneous contacts exteriorly of the unit, the main feed wires being adapted to be attached directly to the unit in a simple and expeditious manner.

A further feature of the invention is to produce a unit which cannot be tampered with, i. 0., one so constructed that curious personscannot possibly dismantle it without, in effect, disrupting it and rendering it unfit for further use.

A still further important feature of the construction is that the possibility of short circuits is entirely eliminated.

Features of the invention, other than those adverted to, will be apparent from the folone end portion of the core and the cooperating plug.

F'gure- 3 is a section on the line 33 of Figure 4; and,

Figure 4 is a section on the line 4.4 of Figure 3.

Referring to the drawings, 1 designates a core shown, in the main, as cylindrical and which core may be constructed from any suitable refractory material capable of withstanding the heat produced by the resistance coil 2 which is wound about the same. The core is provided with two parallel passes 3 and 4 which extend entirely through the same in parallel relation to the axis of the core.

The core isthreaded for the greater portion of its length to provide a helical seat for the windings of the coil 2 in order that successive convolutions of the winding may be properly spaced apart to preclude short circuiting. The opposite end portions of the core are however peculiarly shaped and constitute an important part of this inventlon.

Each end of the core is slotted or channeled as shown at 5 and 6, these channels or slots being so disposed as to extend inwardly from the ends of the core in parallel relation to one another and so that the pars sages 3 and 4, which extend through the core, will extend from the base of one slot to the base of the other. This is clearly shown in Figures 2 and 4.

Spaced equal distances from the opposite ends of the core are two annular grooves 7 and 8 and from the base of the groove 7, upon proceeds, the successive convolutions one end of the core is flattened as shown at 9 in a plane substantially perpendicular to the plane including the axes of the two passages 3 and 4. The same end of the core is also flattened as shown at 10 in a plane parallel to the plane of the flattened surface 9, but the flattened surface 10 extends from the end of the core only a part of the way to the channel 7 being separated there- 'from by a flange 11. The opposite end of the core is constructed the same as the end described, but the parts are reversed. That is to sa the flattened part 1O lies in the same plane as the flattened part 9 while-the flattened part 9? lies in the same plane as the flattened part 10.

This core construction permits of a unique arrangement of the current conveying parts as is apparent from Figure 4. After the core has been constructed in the manner described, I first associate therewith the contact members by means of which electrical connection. with the current, carrying leads of an outside source are connected to the unit and said current fed to the resistance coil. These contacts are preferably in the form of flat strips designated by the reference characters 12 and 14. These strips may be of a single thickness or they may be laminated. In any event, they are of less widththan the diameter of the passages 3 and 4=so that they may extend through these passages in chordal relation to the circular cross sectional sha e of the passages as is clearl shown in wigure 3.

In ringing these strips into position, one end of the strip 12 is. bent so as to extend from abut-ting relation! with a flange 11 longitudinally of and over-the end of the core being thereupon returned upon itself and to extend through the passage 3. At the opposite end of the passage it is bent up wardly andover the end of the core and inwardlyalong the flattened portion 9 to the base of the channel 7 where it is turned up to leave a free end 15 as shown in Figure 4.

The other strip 14 starts in abutting relation to the flan e 11, extends around the adjacent end of t e core and after passing through the passage 4 is bent around the opposite end of the core and returned along the flat surface 9" to be bent outwardly as shown in 15. Vhen the parts have been brought into these positions, the resistance coil may be applied.

It may be started anywhere in the channel 7 and during its first convolution is wrapped f ovr the strip 12, which strip is thereupon turned down over the first convolut ion .designated 2 in Figure 1, so as to the winding at this point and form a electrical contact with the strip 12..

winding of the resistance coil thereheiug added and conforming to the helical threaded contour of the core until the op posite end of the core is reached. The last couvolutions 2" will occupy the groove or channel 8 and will wrap about the strip 14 adjacent the base of the projection 15 which is thereupon turned down as shown at the right hand side of Figure 1 to make good electrical connection with this convolution of the coil.

\Vhen the parts are thus far assembled, it will he manifest that the strips are locked against longitudinal shifting and while one end of each strip is given a good electrical contact with the corresponding end of the coil, the other end of such strip is electrically insulated from the other end of the coil by the interposed flange 11 which will positively preclude short circuiting. It

will moreover be noted that no extraneous attaching means have been employed and no parts have been used which are apt to get out of order or become disarranged or displaced.

The unit having been thus far assembled, the next step of assembly is to apply a plug 16 to each end of the core. Each plug is provided with a rib or'key 17 shaped com- I plementary to the slots 5 and 6 and these plugs are provided with holes 3 and 4 so positioned that when the plugs are brought into the positions shown in Figure 1, the holes 3" and 4 of both plugs will aline with the corresponding passages 3 and 4 of the (ore while the ends of the keys 17 will enter the slots 5 and 6 and bear against the turned over portions of the stri s 12 and '14. The plugs are held in the pos tions stated by a casing or cover 18, cylindrical in form and adapted to encircle or embrace the assembly throughout its entire length. The outer ends of the plugs are chamfered as shown at 19 and the opposite ends of the casing are pressed or spun in over these chamfers so as to force the plugs firmly against the opposite ends of the cores and at the same time bind the parts firmly together within the smooth exterior casing. As the ends of the casing are spun over and force the plugs tightly against the opposite ends of the core, it is found in practice that the strips 12 and 1 4 are slightly bulged as shown imFigure lfso as to react with yieldingpressuie against the passage of a wire or other circular body through plugs 16 are of nonconductive refractory material, lava being suitable for this purpose. The .casing18 is preferably of metal and is spaced from the resistance-coil '2 so 6 as not to short circuit these coils." If desired-however some refractory material may be wrappel about the coil before the casing is installed so as to positively'preclude short circuiting. Asbestos, mica or other similan 10 substance may be used to advantage in this positioned and extending connections to wvhich current supplying leads have to be attached as heretofore and' in addition to being a self contained unit, it is so conf structed thatafter initial manufacture, it

cannot be taken apart by curious persons but has to be actually disrupted in order to take it apart. Its cost of manufacture howeyer is so'small that repair of such units is not worth while as a new unit is simply substituted for one in case it becomes burned out through the application of too much current to the coils.

The unit may be made very small and is thus particularly useful in connection with 'small tools requiring heat, not only from its compact standpoint but from its ease of attachment and detachment, with reference to the power leads. Thennit moreover may be used in multiple. That is to say, if any particular unit does not'give the desired heat, a number of such units may be threaded after the manner of beadsupon the 'posi- ,tive and negative leads 20 and 2-1 to include said units -1n the electrical circuit in" multi lo. I know of no prior .construction w ich will permit of this highly advantageous arrangement. q i The foregoing detailed description sets forth the invention in its preferred practical form, but the invention is to be understood as fully commensurate with the appended claims.

Having thus fully described the invention;

what we claim as new and desire to secure by Letters Patent is:

1. An electrical unit embodying a core provided with assages extending longitudinally thereof and into which passages positive and negative feed wires of an electric circuit are adapted to be thrust, a coil encircling the core, a contact strip secured .to one end of the coil and extending into one of the passages to form a 'clamping' ,member adapted to clamp the feed wire which isthrust into said passage, and a "second metallic strip secured to the other end of thecoil and extending into the other passage-to forr'rra clamping member adapted -.to clamp the other feed wire when said wire is thrust into said passage, whereby the introduction'of the positive and negative feed. wires into said passages will cause the coil to be included in the circuit of which said wires form a part.

2. An electrical unit embodying a core provided with passages extending longi tric circuit are adapted to be thrust, a coil encircling the core, a contact strip secured to one end of the coil and extending into one of the passages to form a clamping member adapted to clamp the feed wire which is thrust into said passage, and a -tudinally thereof and into which passages positive and negative feed wines of an elecsecond metallic strip secured to the other end of thecoil and extending into the other passage ,toform a clamping member adapted to clamp the other feed wire when said wire is thrust into said passage, whereby the introduction of the positive and negative feed wires into said passages will cause the coil to be included in the circuit of which said wires form a part, a casing enclosing the core and coil, and means for closing the opposite ends of the casing.

" 3; An electrical unit embodying a core provided with passages extending longi-- tudinally thereof and into which passages positive and negative feed wires of an electric circuit are adapted to be thrust, a coil encircling the core, a contact strip secured to one end of the coil and extending into one of the passages to form a clampin member adapted to clamp the feed wire w ich is thrust into said passage, a second metallic 'strip secured to the other end of the coil and extending into the other passage to form a clamping member adapted to clamp the other feed wire when said wire is thrust into said passage, whereby the introduction of the. positive and negative feed wires into said passages will cause the coil to be included in the circuit of which said wires form a part, a tubular sleeve embracing the core and coil and spaced from the latter, end pieces positioned within the opposite ends of the sleeve and beyond the opposite ends of the core and provided wit-h apertures .;lined with the passages in the core, the ends of the casing being turned inwardly over the end pieces to hold said end pieces in position. I

4. An electrical unit embodying a (7018 having two passages extending longitudinally therethroiigh and into which passages .fee'd wires are adapted to, be thrust, a leaf spring positioned i-nteriorly and extending longitudinally of each passage, a coil encircling the core with one end of the coil electrically connected to one leaf spring and the other end of the coil electrically connected to the other leaf spring, whereby said leaf springs will serve to firmly grip the feed wires thrust into the passages and simultaneously include the coil in the circuit.

secured to one end of the coil, extending through one passage and hooked over the opposite end of the core, and a metallic strip secured to the opposite end of the coil extending through the other passage and hooked over the other end of the core, whereby said stri s are secured against movement longitudinally of their respective passages and are adapted to be engaged b positive and negative leads-of an electri circuit forced into said passages for the purpose of including the coil in circuit. (5. An electrical unit embody a core having two passages therethrough, a coil wrapped about the core. a metallic strip secured to one end of the coil, extending,

through one passage and hooked over the opposite end of the core, and a metallic strip secured to the opposite end of the coil extending through the other passage and hooked over the other end of the core,'where-. y said strips are secured against movement longitudinally of their respective passages and are adapted to be engaged by positive and negativeleads of an electrical circuit forced into said passages for the purpose of including the coil in circuit, an

a casing encircling and housing the core and coils and free from engagement with the latter.

7. An electrical unit embodying a core provided with passages extending therethrough, a coil encircling said core, a strip one endof which is secured to one end oi the coil and the strip thereupon passed through one of the passages and returned along the exterior of the core to a point adjacent but spaced from the contiguousend of the coil, a second strip secured the last mentioned end ofthe coil and passing through the other along the outer perip cry of the core to a point adjacent to'but spaced frolnth contiguous'end of the coil, whereby said strips constitute terminal contacts of the coil adapted to be en aged by positive and negative leads intro uced into the passages of the core.

8. An electrical unit embodying a core provided with two passa es extending therethrough, a strip extending through each passage, the opposite ends of each strip being hooked over the ends of the core to retain the strips against longitudinal movement, a coil secured to the end of one strip,

and helically wound about the exterior of the core to adjacent the opposite end thereof where it is secured to the end of the other strip, whereby said strips constitute the terminal contacts of the coil and are adaptassage and returned ed to be en aged by positive and negative wires intro uced into the passages of the core for the purpose of including the coil in circuit.

.9. An electrical unit embodying a'corc provided with two passages extending theiethrough, a strip extendin through each passage, the opposite en of each strip being hooked over the ends of the core to retain the stripsagainst longitudinal movement, a coil secured to the end of one strip and helically wound about the exterior of the core to adjacent the opposite end thereof where it is secured to the end of the other strip, whereby said strips con-- stitute the terminal contacts of the coil and are adapted to be engaged by positive and negative wires introduced into the assages ofthecore for the purpose of inclu ing the coil in circuit, that ortion of the exteriorof the core which t e coil embraces bein longitudinally threaded to rovide a helica seat for the coil'to preclu e adjacent 'convolutions of the coil from contact with one other strip, whereby said strips constitute the terminal contacts of the coil and are adapted to be en aged by positive and negative wires intro uced into the passages of the core for the pur ose of including the coil in circuit; a tubu ar casing surrounding the coil and core and extending beyond the ends of the latter, plug members positioned within the opposite ends of the'casing and having apertures alined with the passages in the core, the opposite ends of the casing being turned in over the plug members to maintain them in position and to hold the parts inassembled relation.

electrical unit embodying a core provided with two passages extendin therethrough, a strip extending through each assage, the opposite ends of each strip eing hooked over the ends of the core to retain the strips against longitudinal movement, a coil secured to the end of one strip and helically wound about the exterior of the core to adjacent the opposite end thereof where it is secured to the end of the other strip, whereby said strips constitute the terminal contacts of the coil and are adapted to be engaged by positive and negative wires introduced into the passages of the core for the purpose of including the coil in circuit, a tubular casing surrounding the coil and core and extending beyond the ends of the latter, plug members positioned within the opposite ends of the easing and having apertures alined with the passages in the core, the opposite ends of the casing being turned in over the plu members to maintain them in position an to hold the parts in assembled relation, each In member ha a key and slot coniieet ion with'the fiacent end of the core 10 to maintain the apertures of the plugin alinement with the passages of the core.

In testimony whereof we have signed the foregoing specification.

LEONARD E. STEDIER. FLOYD P. SMITH. 

